61434-45-5

Upstream product

• 92-52-4 biphenyl 
• 187737-37-7 propene 

Relevant academic research and scientific papers

Shape-selective alkylation of biphenyl with propylene using zeolite and amorphous silica-alumina catalysts

The influence of zeolite structure for the alkylation of biphenyl with propylene was studied over various zeolites such as HY, HZSM-5, and dealuminated mordenite (DMOR), as well as amorphous SiO2/Al2O 3, in a stirred tank reactor. Biphenyl conversion was found to increase with reaction time for HZSM-5 and DMOR zeolites and reach a leveling off in 4 h, whereas for HY and amorphous SiO2/Al2O 3 a leveling off was reached within an hour. DMOR displayed the highest selectivity for 4,4′-diisopropylbiphenyl (4,4′-DIPB) even at temperatures as high as 300 °C, whereas for HY, HZSM-5 and amorphous SiO2/Al2O3 selectivities fell in the range of 10-35%; they were significantly lower than observed for DMOR. These differences in selectivity might be due to the structure and pore channels of the zeolites. DMOR was found to be an active catalyst, the selectivity for 4-isopropylbiphenyl (4-IPB) and (4,4′-DIPB) was high among isopropylbiphenyl (IPB) and diisopropylbiphenyl (DIPB) isomers, respectively, indicating DMOR possesses shape-selectivity. The selectivity of 4,4′-DIPB increased with time, while the corresponding selectivity of 4-IPB decreased for DMOR catalyst. Alkylation of biphenyl with propylene occurred with predominant formation of 4-IPB in the first step. 4-IPB is only a source in the second step of alkylation of biphenyl with propylene for the formation of 4,4′-DIPB, while 3-IPB does not participate in the formation of DIPB isomers.

The alkylation of biphenyl over one-dimensional twelve-membered ring zeolites. the influence of zeolite structure and alkylating agent on the selectivity for 4,4'-dialkylbiphenyl

Alkylation, i.e., isopropylation, s-butylation, and t-butylation, of biphenyl (BP) was examined over one-dimensional twelve-membered (12-MR) zeolites: Mordenite (MOR) and SSZ-24 (AFI) with straight channels, and SSZ-55 (ATS) and SSZ-42 (IFR) with corrugated channels. Types of zeolites and alkylating agents highly influenced the selectivities for dialkylbiphenyl (DABP) isomers. Shape-selective formation of 4,4'-diisopropylbiphenyl (4,4'-DIPB) was observed over MOR and AFI; however, ATS and IFR gave 4,4'-DIPB only in low selectivities at 250°C: 87% over MOR, 60% over AFI, 20% over ATS, and 30% over IFR. The selectivities for 4,4'-di-s-butylbiphenyl (4,4'-DSBB) in the,s-butyl-ation were higher than those for 4,4'-DIPB: 95% over MOR, 85% over AFI, 75% over ATS, and 50% over IFR. The t-butylation afforded selectively 4,4'-di-t-butylbiphenyl (4,4'-DTBB) over the zeolites: 96-97% over MOR and AFI, 90% over ATS, and 80% over IFR. These results in the alkylation indicate the exclusion of 4,4'-DABP from other bulky DABP isomers by steric restriction in zeolite channels is an important key for the high shape-selectivity. Even zeolites with large channels, such as ATS and IFR, can have shape-selective nature if the bulky moieties, such as,s-butyl and t- butyl groups, are large enough to differentiate the transition state of the least bulky 4,4'-DABP from those of the other isomers inside their channels. The selectivity for 4,4'-DABP decreased at high temperatures in some alkylations: isopropylation over MOR, and s-butylation and t-butylation over MOR, AFI, and ATS. The decreases are due to the iso-merization of 4,4'-DABP at external acid sites, because the channels are not large enough for the isomerization of 4,4'-DABP to bulkier 3,4'-DABP. However, the isopropylation over AFI was accompanied by the isomerization of 4,4'-DIPB at external and internal acid sites, because the channels are large enough for the isomerization of 4,4'-DIPB.